1) Consider verifying the response either by asking more details (for example, Who was the veterinarian?) or, in the case of products, asking if you can see it.
2) Be clear about what exact service or product you are asking about (e.g. do not ask whether a person bought “agricultural inputs”). Always ask about the same product / service – do not mix different products / services together.
3) Consider asking people who responded “no” why they did not use the product / service – it can provide you with very useful data for adjusting the project’s promotion-related activities.
4) In the case of services / products that can be accessed by different household members (e.g. veterinary services), sometimes it is better to ask not whether “… did you use …” but “… did you or your household members use …”. This will help you avoid underestimating the usage of the given service / product.
5) Consider also assessing how often the respondent used the promoted service / product, so that you can measure any frequency-related changes. You have two options for gaining the required data:
- If the respondents are likely to remember the frequency (because you use a short recall period or because it is likely that the person used the product / service a few times only), you can ask: "In the past [specify the time period], how often did you purchase/ use [specify the service / product]?"
- If the respondents are not likely to remember the frequency, ask: "Can you please tell me when did you last use [specify the service / product]?". While it is possible that a person used the service / product, for example, yesterday but otherwise s/he uses it only once per year, in the total sample of your respondents, such 'accidental' facts cancel each other out and you gain more reliable frequency data than you would get if you had asked "How often ...?"